Ulcer - an open sore on the skin surface or on the stomach lining.
Ulcerative colitis - a serious disease that causes ulcers and irritation in the inner lining of the colon and rectum.
Ulnar bone - the longer of the two bones in the forearm.
Ultrasound (Also called sonography.) - a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.
Ultraviolet radiation - invisible light rays that come from the sun. Ultraviolet radiation can damage the skin and cause melanoma and other types of skin cancer.
Umbilical cord - a rope-like cord connecting the fetus to the placenta. The umbilical cord contains two arteries and a vein, which carry oxygen and nutrients to the fetus and waste products away from the fetus.
Umbilical cord blood transplant - a procedure in which stem cells which were taken from an umbilical cord immediately after delivery of an infant are given to a person through an IV to treat certain conditions.
Umbilical hernia - a weakness in the abdominal muscles which can cause an outward bulging of tissue and/or organs in the abdomen.
Unilateral - affecting one side of the body. For example, unilateral kidney cancer occurs in one kidney only.
Upper GI (gastrointestinal) series (Also called barium swallow.) - a diagnostic test that examines the organs of the upper part of the digestive system: the esophagus, stomach, and duodenum (the first section of the small intestine). A fluid called barium (a metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up on an x-ray) is swallowed. X-rays are then taken to evaluate the digestive organs.
Urea - the nitrogen part of urine produced from the breakdown of protein.
Urea breath test - test used to detect Helicobacter pylori (H. pylori) infection. The test measures breath samples for urease, an enzyme H. pylori produces.
Ureterocele - a condition in which the portion of the ureter closest to the bladder becomes enlarged because the ureter opening is very tiny and obstructs urine outflow; urine backs up in the ureter tube.
Ureteroscope - an optical device which is inserted into the urethra and passed up through the bladder to the ureter; used to inspect the opening of the ureters.
Ureters - two narrow tubes that carry urine from the kidneys to the bladder.
Urethra - narrow channel through which urine passes from the bladder out of the body.
Urethritis - an infection limited to the urethra.
Urge incontinence - leaking of urine due to a muscle spasm or contraction. This can occur even when the bladder is only partly full.
Urgent surgery (Also called emergency surgery.) - an operation performed immediately as a result of an urgent medical condition.
Urinalysis - laboratory examination of urine for various cells, substances, and chemicals, such as red blood cells, white blood cells, infection, or excessive protein.
Urinary incontinence - the loss of bladder control.
Urinary retention - the inability to empty the bladder.
Urinary tract infection (UTI) - an infection that occurs in the urinary tract; often caused by bacteria such as Escherichia coli. A urinary tract infection often causes frequent urination, pain, and burning when urinating, and blood in the urine.
Urine flow study - a test in which the patient urinates into a special device that measures how quickly the urine is flowing. A reduced flow may suggest benign prostatic hyperplasia(BPH).
Urogenital - refers to the urinary and reproductive systems.
Urology - the branch of medicine concerned with the urinary tract in both genders, and with the genital tract or reproductive system in the male.
Urticaria (Also called hives.) - a condition in which red, itchy, and swollen areas appear on the skin - usually as an allergic reaction from eating certain foods or taking certain medications.
Urushiol - a resin found in poison ivy, poison oak, and poison sumac plants that causes an allergic skin reaction.
Usher syndrome - a hereditary disease that affects hearing and vision.
Uterine wall - the wall of the uterus.
Uterus (Also called the womb.) - a hollow, pear-shaped organ located in a woman's lower abdomen, between the bladder and the rectum, that sheds its lining each month during menstruation and in which a fertilized egg (ovum) becomes implanted and the fetus develops.